Automation, as the word suggests, is a framework of automating a particular task by understanding, interpreting, and creating logic. This includes enhancing the current capabilities of the tasks that are done manually and reducing the error rate of those tasks while focusing on scaling the task with reduced effort.
As an example, imagine we need to upgrade the IOS image of a Cisco router. This can involve multiple tasks, such as loading the image on the router, validating the checksum of the image, offloading traffic (if it's a production router), modifying the boot variable, and finally, reloading the router with the new image.
All of this is feasible if we have only one router to upgrade. Now take a similar scenario and try to implement it for around 1,000 routers.
Let's say we take 30 minutes getting each router to perform the aforementioned tasks. It's an easy calculation of 1000*30=30,000 minutes of manual effort.
Also, if we are performing tasks on each router manually, think of the errors that can creep in.
Network automation would be helpful in this scenario, as it can take care of all the preceding aspects and perform the tasks in parallel. Hence, if it takes 30 minutes of manual effort for one router, and in the worst case scenario the same 30 minutes for automation to perform the same task, then parallel execution would result in all 1,000 routers being upgraded within the same 30 minutes.
Hence, final amount of time will be only 30 minutes, irrespective of the number of routers you throw at the automation framework. This also drastically reduces the need for manual work, and an engineer can focus on any failures in the 1,000 network devices.
In the upcoming sections, I will introduce you to some of the concepts, tools, and examples that will get you started with building automation frameworks and effectively using them in network scenarios to perform network-related activities.
This also assumes that you have an idea of network concepts and common terminology used in networking.
Some of the examples that I will provide assume familiarity with syslog, TACACS, basic router configs such as hostnames, iOS image loading, basic routing and switching concepts, and Simple Network Management Protocol (SNMP).